TACOMA — Driven by jealousy, a 22-year-old Fort Lewis soldier fatally shot a Parkland couple in their home, poured acid over them in an attempt to dispose of the bodies and then kidnapped their 6-month-old daughter, according to court documents.

Spc. Ivette Gonzalez Davila killed fellow soldiers Randi Miller and her husband, Timothy Miller, on Saturday because she believed Randi was having an affair with another man who was Davila’s former boyfriend, prosecutors wrote in a declaration of probable cause filed Monday in Pierce County Superior Court.

“Davila told [another] soldier that Randi Miller was in a relationship with Davila’s ex-boyfriend, another soldier, who had apparently chosen Randi Miller over Davila,” Pierce County Deputy Prosecutor Ed Murphy wrote in the declaration.

Davila, of Bakersfield, Calif., is being held in Pierce County Jail on investigation of homicide and kidnapping. She is expected to be charged Wednesday in connection with the slayings, Murphy said.

Davila, a specialist in the I Corps and a member of the Fort Lewis color guard, was arrested Sunday after she told a soldier she had killed Randi, 25, and Timothy, 27, and took their baby, Murphy said. Davila brought the baby to Fort Lewis after the slayings, according to court papers.

Davila was ordered held without bond after a brief court appearance Monday in which prosecutors asked for a 72-hour extension on filing charges while they work out jurisdictional issues with the military.

The extension was granted based on information gathered by military police and contained in the probable-cause document.

Randi and Timothy Miller were also stationed at Fort Lewis, according to a base spokesman. Entries on the MySpace pages of the victims include messages from Davila, indicating that she knew both.

According to the declaration of probable cause, a soldier reported on Sunday that he had helped Davila bring some baby items up from her car to her barracks room and helped her feed the 6-month-old child she initially said she was baby-sitting. Davila later told the soldier on Sunday that she had “killed the baby’s parents the night before,” according to the declaration.

Police and prosecutors said they do not believe the shootings were motivated by the kidnapping.

Davila told the soldier that she had gone to the couple’s home armed with a handgun because she believed she had been dumped by an ex-boyfriend over Randi Miller, the declaration states.

According to the declaration, the unnamed soldier said Davila told him she shot Randi Miller while Randi was in bed and then shot Timothy Miller while he was taking a shower.

Davila cleaned up as much as she could, took the couple’s baby and drove to a Home Depot to buy some muriatic acid, according to the declaration.

She then allegedly returned to the couple’s home, dragged the body of Randi Miller into the bathtub and poured the acid on both bodies “to get rid of them,” court documents say.

Military police reported that they had recovered a handgun, a receipt from Home Depot for the acid and Randi Miller’s purse from Davila’s barracks at Fort Lewis, court documents say. The documents do not say where the baby was found.

“Always very nice”

Davila’s grandfather, Ramiro Gonzalez, said she was the middle of three girls who grew up in Bakersfield in California’s southern San Joaquin Valley.

She was very religious until she joined the Army, he said.

“There she pulled back a little,” her grandfather said, “but her behavior was always very nice.”

Davila’s mother, Maria Gonzalez, was distraught when reached by phone on Monday.

She said she thought that her daughter had turned herself in to authorities but did not have many details of what was being alleged. She said her daughter had not served in Iraq.

Relatives of the Millers expressed skepticism and disbelief at the alleged motive for the slaying, saying they didn’t believe Randi had been having an affair.

“They had a beautiful marriage,” said Randi Miller’s father, Robert Blanchard of Laconia, N.H. “What did [the suspect] say, ‘I’m going to shoot you ’cause I’m not as good as you?’ That’s just great.”

Heather Keene, a friend of Timothy Miller’s family, said both Timothy and Randi were medics who had reached the rank of sergeant.

They met while in the Army and married about five years ago while they were stationed in South Korea, according to their relatives. The Millers moved to their Parkland home about three years ago, when they purchased two adjoining properties and fixed both up, neighbors said.

They lived in one and rented out the other.

According to neighbor Marcus Sims, the couple bought another rental in Pierce County last year and gave birth to their first child, Kassidy.

Keene said Timothy Miller “lived for his daughter. He and his wife were very loving to each other and to their daughter and that’s all they concentrated on.”

Both were hard-working, lovely people, said Sims, who fished with Timothy and whose wife occasionally baby-sat for the couple.

“They were the neighbors to call if you needed anything,” Sims said.

Relatives said Timothy Miller, originally of Gardnerville, Nev., east of Lake Tahoe, had been in the Army for 10 years and had served two tours in Iraq. Randi Miller had served one Iraq tour, her family members said.

Kassidy is now in the care of the state Child Protective Services agency. According to family members, the baby will be picked up by relatives of Timothy Miller.

Lt. Gen. Charles H. Jacoby Jr., commanding general of the I Corps and Fort Lewis, issued a statement Monday that read: “This is a tragic situation for all concerned. The entire Fort Lewis community grieves for this family’s loved ones and friends. We pledge our support to them in this time of tragedy. We will do everything possible to assist local authorities in this joint investigation.”